The U.S. Census Bureau has never asked Americans about sexual orientation and gender identity. Last year, though, requests for that data came from more than 75 members of Congress and multiple federal agencies.

Still, the Census Bureau concluded "there was no federal data need" to collect this information, the bureau's outgoing director, John Thompson, wrote in March.

A document obtained by NPR through a Freedom of Information Act request, however, reveals that the Department of Housing and Urban Development told the bureau that there indeed was a need.

"Valid, reliable, and nationally representative data on sexual orientation and gender identity are essential to HUD fulfilling its mission," former HUD Secretary Julián Castro wrote in a letter to Thompson dated June 30, 2016.

The release of the HUD letter comes about a month after Democratic Sens. Tom Carper of Delaware and Kamala Harris of California asked Thompson in a letter to provide an explanation by Monday about how the Census Bureau decided to not add sexual orientation and gender identity as a proposed topic for the American Community Survey.

As of Monday evening, spokespeople for both senators' offices said they had not yet received a response. Read more via NPR